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Early LaserWriter ROM dumps

mcpublic

Member
I've already looked and am pretty certain most of it was written in C
I just read Crispin Goswell’s 1987 paper “An Implementstion of PostScript.” Besides the fact that I believe you intrinsically, this reminder of the complexity of the language itself and the graphics algorithms leads me to concur. My “monkey’s uncle” statement was an inference based on the vast majority of early Macintosh apps being written in assembly language, and the mistaken assumption that the ROMs were “small.” From my memory of the MAME dump table: 64kB x 2 x 8 = 2MB. This is “big.” But the LaserWriter Plus also included a dozen fonts, right?
 

NJRoadfan

Well-known member
PostScript being written in C makes sense. Adobe was selling the interpreter to vendors who would be using a variety of CPU architectures in their printers. The vast majority of early PostScript printers were 68k based, but that may have to do with maintaining compatibility with Apple's products. The early LaserWriter drivers were notorious for sending binary blobs of 68k machine language in the LaserPrep file to implement new printing features.

Running PostScript on a 300x300dpi printer with a 10Mhz 68k was never going to be fast even if it was written in pure ASM. It's a ton of pixels to rasterize for something made in 1985. Added overhead also comes from the fact that the LaserWriter driver does not completely convert all QuickDraw objects to PostScript routines. A lot of that heavy lifting is done in the printer by routines contained in the LaserPrep file.
 

compu_85

Active member
Attached are the ROMs from a LaserWriter IIG, v1.0 and 2.0.

The 1.0 ROMs are window'd EPROMs, the 2.0 are mask roms. There's a jumper on the board to select "2 MB" or "4 MB", the 1.0 roms are set for 2mb, 2.0 is set for 4mb.

-J
 

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  • lwiig_1.0_341-0861_lm.BIN
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compu_85

Active member
Here's the firmware from a LaserWriter IIsc board, "Personal Laser" Version 1.0

** (c) Apple Computer, 1987 ** ** Hardware: Mike Flora ** ** Firmware: Tad Browne **
 

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compu_85

Active member
And to the OP's first question, here are the ROMs from a LaserWriter (not Plus).

Hope that helps!

-J
 

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  • lw_342-0086a_h2.BIN
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  • lw_342-0085a_l2.BIN
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compu_85

Active member
There's an error with the 2.0 ROMs I posted earlier... turns out these use 27C080's instead of 27C040's.

Now the 4M selection on the logic board makes more sense :)
 

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danda

Well-known member
And to the OP's first question, here are the ROMs from a LaserWriter (not Plus).

Hope that helps!

-J
That’s amazing! Thank you for sharing these!

I now really want to downgrade my LaserWriter (which was previously upgraded to a Plus). Any tips on how I should do this? I know a bit about hardware, but not about ROM dumping or burning. Is there modern EEPROMs that would be drop in replacements?
 

compu_85

Active member
Does your machine have erasable ROMs now? (little window under the sticker). If so you can just erase them and program in the older code.

Besides the extra fonts and bug fixes, are there any differences between the plus and original LW?

-J
 

danda

Well-known member
Does your machine have erasable ROMs now? (little window under the sticker). If so you can just erase them and program in the older code.

Besides the extra fonts and bug fixes, are there any differences between the plus and original LW?

-J
I would assume it doesn’t have erasable ROMs. I’ve never looked at the controller board, but my assumption is that it was upgraded from an original to a Plus in the 80s, and never touched since. (I’ve had it 10 years now.) I’ll have a look this weekend though. If it’s not got erasable ROMs, so you know of any I could get that would be compatible?

I think it was just the extra fonts and an upgrade of PostScript that the Plus ROMs gave it. The reason I want to downgrade it is I have two machines - this one an original upgrades to a Plus (so the sticker on the back just says “LaserWriter”), and the other one was sold as a Plus. And I’d like to have them back to their original state, rather than just having two Pluses.
 

Sword7

New member
Ok, I now found this forum because I am new to this. I was searching for LaserWriter ROM dumps, etc. because they are based on HP LaserJet laser printers. Is that possible to make ROM dumps from HP LaserJet laser printers also? HP LaserJet printers use 68000 processor too.
 

NJRoadfan

Well-known member
The HP LaserJet is NOT based on the LaserWriter. Both printers use the same Canon LBP-CX laser printer engine however.
 

al kossow

Active member
It is possible to dump them. I've had an original LaserJet PCB for a while now that I've been meaning to dump.
The firmware is much smaller than Apples
 

Sword7

New member
The HP LaserJet is NOT based on the LaserWriter. Both printers use the same Canon LBP-CX laser printer engine however.

Yeah. You are right. I read Wikipedia and it said that HP LaserJet is based on Canon LBP-CX engine.

I noticed that current MAME (/src/mame/apple/lwriter.cpp) still show skeleton flag. Are you trying to get it working?
 

Sword7

New member
It is possible to dump them. I've had an original LaserJet PCB for a while now that I've been meaning to dump.
The firmware is much smaller than Apples

Yeah. I am looking for LaserJet ROM dumps because it uses PCL protocol for printouts and HP-GL protocol for plotter.
 

Sword7

New member
I researched more. I now learned that LaserWriter II series use Canon SX engine. It is compatible with CX engine that I think so. LaserJet II and III are based on SX engine. LX engine is for personal laser printers like LaserWriter NT, LaserJet IIP and IIIP. LX/SX engine uses 68000 processor. I found postscript cartridges (ROM dumps) for LaserJet II and III printers but need PCL4 firmware dumps. I was looking for LX/SX service manuals but can't find them so far.

I found EX service manual (LaserJet 4 and LaserWriter Pro 600 series uses for 600-dpi printing), CLBP 360PS and 460PS service manuals (color laser printers - Color LaserWriter and Color LaserJet 4500 series). They can be implemented on MAME emulator but needs additional firmware ROM dumps. There are so many Canon service manuals for Laser and Inkjet printers.
 

absurd_engineering

Well-known member
Howdy! Slight digression — I'm working on a LaserWriter IIg, specifically, trying to determine if there's code in the ROMs to support FPU operations if the empty 68882 socket were populated. I have images of the early and late ROMs, but I'm unsure of the interleaving scheme... any chance you have IIg ROMs already combined, or could instruct me in the use of your Go tool to combine them?

Thank you!
 

al kossow

Active member
for the LW Plus completeists, there is an upgrade rom set on ebay that hasn't been dumped but I don't feel like spending $100 for it.
it looks like one with just higher density roms
 

danda

Well-known member
I saw that, but it's the actual upgrade kit - I'm trying to find the original non-plus ROMs. There was an upgrade kit on ebay in 2019 which had the original ROMs (presumably the owner had upgraded their LaserWriter, and then put the old ROMs in the box for safe-keeping) but they wouldn't ship it overseas so I didn't get it.
 
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